Electric-arc lamp.



5 SHEETS-SHEET 1 PATENTBD AUG.-

B. A. STOWE. ELECTRIC ARG LAMP.

APPLIOA'I'IDE FILED D20. 5, 1902.

WJTNESSES' PATENTS!) AUG. 8, 1985.

B. A STOWB.

ELECTRIC ARC LAMP.

APPLIGATIDH EH-ED mm. 5, 1902.

5 SHEETS-SHEET 13 INVENTOR No. 796,467. PA TBNTED AUG. 8, 1905. B. A.STOWB.

ELEGTRIG ARC'LAMP.

APPLICATION FILED D30. 5, 1902.

5 SHEETS-SHEET 5 TNESSES fNVE TOR W 7 7 I Attorntjr UNITED STATES PATENTOFFICE.

BERNARD A. STOWE, OF CLEVELAND, OHIO, ASSIGNOR TO THE JANDUS ELBXTRIUCOMPANY, OF CLEVELAND. OHIO.

ELECTRIC- Specification of Letters Patent.

ARC LAM P.

Patented Aug. 1905.

.To (M11 whom. I H'MLI/ UUILUVI'H/ Be it known that I, BERNARD A.S'rowu, a resident of Cleveland, in the county of Guyahoga and State ofOhio, have invented certain new and uscfullmprovements in Electric-ArcLamps; and I do hereby declare the following to be a full, clear, andexact description of the invention, such as will enable others skilledin the art to which it appertains to make and use the same.

My invention relates to improvements in electric-arc lamps, one objectof the invention being to so construct the lamp that it will be readilyadaptable for use on constant-potential circuits with currentsot'ditferentvoltage. either direct or alternating, and which can bereadily converted from one type of arc-lamp to another and in accordancewith the current or circuit (whether constant current or constantpotential) with which it may be desired to use the lamp without alteringor disturbing the general lamp structure.

A further object is to improve the lamp shell or casing and so connectit with the framework that it can be lowered bodily with the globe toexpose the entire mechanism of the lamp.

A further object is to produce a general lamp structure which will admitof the removal of one regulating mechanism and the insertion of another.

A further object is to provide means to facilitate the insertion ofupper carbons of dill'erent lengths into a holder within aguidetube.

A further object is to provide a support for a resistance-coil which canbercadily assembled and secured in place in the lamp structure and whichcan also be easily removed therefrom.

A further object is to so construct a resistance-coil as to minimize theextent of bearing' surface thereof against its support to facilitateventilation of the coil.

A further object is to so construct and arrange a resistance-coil andits support as to insure adequate ventilation of said coil.

A further object is to provide improved controlling and regulatingmechanism for an arc-lamp which can be used on constant-pd tcntialcircuits of dilierent voltage and with director alternating currents.

A further object is to construct'and arrange the solenoids of theregulator in such manner that accurate alinemcnt of the cores with thebores oft-he spools will be insured under all conditions.

A further object is to provide simple means for adjusting the coresrelatively to the coils of the solenoids according to the voltage on thecircuit in which it may be desired to use the lamp.

A further object is to provide an improved air-pot for anarc-lamp-regulator mechanism.

A further object is to so construct the plunger of the air-potas toinsure the uniform action of the same. I

A further object is to provide an air-pot construction in which theresistance exerted by the same to the movement of parts connected withit will not only be uniform, but can b: adjusted to suit the conditionsexisting in a lamp of a certain type and the character of the circuit inwhich it is placed.

A further object is to improve the construction of an electric-arc lampin its various details and to render it capable and eflicicnt in theperformance of all its functions.

With these objects in View the invention consists in certain novelfeatures of construction and combinations and arrangements of parts, ashereinafter set forth, and pointed out in the claims.-

In the accompanying drawings, Figure 1 is a sectional view of anelectric-arc lamp cmbodying my improvements. Figs. Qand 3 are enlargeddetail views, partly in section, showing the regulator mechanism. Fig. 4is an enlarged plan view showing the regulator mechanism. Figs. 5 and 6are views illustrating the air-pot construction. Fig. 6 is a viewillustrating the manner of adjustingthe air-pot plunger. Figs. 7 and 8are detail views of the clutch. Fig. 9 is a detail sectional view of thecap or hood of the lamp-casing. Fig. 10 is a detail view illustratingthe resistancecoil and its support. Fig. 11 is a plan view illustratinga portion of the support for the resistance-coil. Figs. 12. 13, and 14.illustrate certain detail views. Figs. 15, 16, and 17 are diagrams ofcircuits for one hundred and ten volts, two hundred and twenty volts,and alternating-current circuits, respectively.

1 represents the main shell or body portion of the lamp-casing, havingan enlarged upper portion 2 and an enlarged lower portion 3. The shellor body 1, with its enlarged ends is constructed of a single piece ofsheet metal bent into cylindrical form and having its meeting edgespermanently secured together by means of solder or otherwise. Theintermediate portion of the shell is strengthened by a series ofvertical corrugations 4, and the upper enlarged portion 2 is similarlystrengthened by means of horizontal annular corrugations 4. A cap orhood 21 is disposed over the upper enlarged end of the shell or casingand provided with a peripheral flange 6, (preferably curvedtransversely,) which projects outwardly from the shell and acts as awatershed and also to preclude the entrance of dust and dirt into thecasing. At diametrically opposite points blocks 7 are secured within thecurved flange 6 of the hood, and each of these blocks is provided with alug 8. The lugs 8 enter L-shaped slots 9, located at diametricallyopposite points in the upper portion 2 of the shell or casing, and arenormally prevented from escape from the horizontal arms of these slotsby means of a thumb-screw 10, passed upwardly through the flange 6 andentering one of the slots 9 behind the lug therein. The shell or casingis thus connected with the hood by bayonet-joints normally locked by athumb-screw 10. A bracket 11 is secured centrally upon the hood for thereception of an insulator 12, to which a link 13 is attached for thereception of suitable suspending devices. The only openings in the topof the hood are the holes 14 for the accommodation of the binding-postsfor the leading-in wires. The metal of the hood surrounding the holes 14is pressed outwardly to form flanges 15, over which caps 16 are fitted.These caps have inwardly-turned flanges at their upper ends, and onthese caps binders 17 are seated and provided with depending flanges 18to act as water-sheds, insulating material 19 bein g disposed betweensaid binders and the caps 16. A block 20, located within the upperportion of the hood 21, is provided atdiametrically opposite points withperforated arms 22,seated against insulating material 23, disposedbetween said arms and the hood. Screw-bolts 24 are passed upwardlythrough the perforated arms 22 (but insulated therefrom) and enterthreaded socketsin the binders 17. The central portion of the block isprovided with an internally-threaded enlargement 25 for the reception ofthe threaded upper end of a tube 26, and said tube is prevented fromturning by means of a screw 27. The tube 26 receives the upper carbon ofthe lamp, constitutes the backbone of the lamp-frame within the casing,and supports most of the mechanism, internal structure, and inner globe,as will be more fully hereinafter explained.

Returning now to the lamp shell or casing, attention is directed to anannular bead forming an internal groove 28 in the lower enlargement 3 ofthe shell 1, below which bead the enlargement curves inwardly andterminates in an opening 29. A cast-metal ring 30 is seated at itsperiphery in the groove 28, and its internal wall is engaged by theupper end of a cylindrical shell 31, the upper edge of which is spunover the cast ring, and immediately below said ring the shell-section 31is made with an outwardly-projecting bead 32. The ring 30 is thussecured at its inner edge to the shell-section 31 and at its peripheryto the enlarged lower end 2 of the main body portion 1 of the shell orcasing. The cast ring 30 is provided with holes for ventilatingpurposes. The cylindrical shell-section 31 is provided at its lower endwith a seat 33 for the outer globe, and at the juncture of said seatwith the shell-section 31 notched brackets 34 are secured for thereception of the bails 35 of the globe-holder 36. The globe-holder 36consists of a band of wire having eyes at its ends for the passage of asuitable bolt or other clamping device, and at diametrically oppositepoints said band is made with loops 37', with which the bails 35' havehinge connection. The globe-holder embraces the neck of the globe, andwhen the bails 35' are made to engage the notched brackets 34 the mouthof the globe will be held firmly against its seat.

From the construction and arrangement of parts above described it willbe seen that when the upper end of the thumb-screw 10 is removed fromthe slot 9 in the shell or casing the latter after a slight turn can bedropped bodily, carrying also the outer globe with it and exposing theentire internal structure of the lamp. This not only gives free accessto the interior of the lamp for trimming, but it also exposes theregulating mechanism, which can be readily adjusted or altered toaccommodate currents of different voltage or to adapt the lamp fordirect or alternating currents or even to remove one regulatingmechanism and substitute another.

The lower end of the carbon-guide tube 26 extends through a threadedhole in the head 38 at the upper endof a cylinder 39, of cast metal, andprojects partly through said cylinder. The cylinder and tube areprevented from turning relatively to each other by means of a screw 40passing through the head of the cylinder and entering a hole in thetube. Amovable carbon-holder 41 is located within the tube 26 and hasconnected with it a flexible conductor 42, which is coiled within thetube and extended from the upper end thereof for connection with theregulating mechanism of the lamp. The carbon-holder 41 is provided onits upper end with a shank 43, which abuts against the closed head 14 otthe tube when a long carbon rod is forced upwardly into thecarbon-holder in trimming the lamp. in some types of lamps, however,short upper carbons are used. For instance, in an alternating-currentlamp an upper carbon eight or ten inches long is usually employed. Itwould not be convenientand,in fact,it would be practically impossiblefor the trimmer to press such a short carbon up into the tube far enoughto cause the shank of the carbonholder to engage the head of the tube,and consequently a carbon of such short length could not be forced intothe carbon-holder in this way. To provide forsueh acontingency, thedevices now to be described may be employed. Atuhular screw 43' ispassedthrough the wall of the cylinder 39 and made to project into the latter.The other or plain end of the screw projects outwardly beyond thecylinder 39 and is made with an elongated slot 44'. A pin 45 is mountedto move ion gitudinally through the tube 43', and in alinement with thispin the carbon-tube 26 is made with a hole 46. A screw 47, projectingdownwardly from a flange 48 on the cylinder, prevents the escape of thepin 45 from the tubular screw, and an arm 49 on the pin normally engagesthe end of the tubular screw to prevent the pin from entering theguidetuhe 26. Now when it is desired to insert'a short upper carbon thecarbon-holder 41 is permitted to descend until the head 50 thereof hasmoved below the hole 46 near the lower end of the carbon-guide tube 26.The pin 45 is now turned until its arm 49 alines with the slot i l ofthe tubular screw, when the operator will press the pin forwardly andcause its end to pass through the hole 46 in the tube 26 and becomedisposed over the head of the carbonholder. The trimmer can now pressthe carbon into the holder, the pin 45 acting as an abutment for thelatter. The short carbon having thus been pressed firmly into itsholder, the trimmer will withdraw the pin 45 to the position shown inFig. 1 to permit the carbon and its holder to move a proper distanceupward in the tube.

The head 38 of the cylinder 39 bears against the lower face of a flangedsleeve 51, of yulcabeston or similar material, through which sleeve thecarbon-guide tube also passes. An annular plate 52 is disposed upon theflange of the sleeve 51 and is made wit-h an integral collar 53-,embracing the sleeve 51. The plate 52 constitutes the clam p-floor andis secured in place by means of a series of screws passing through theplate (but insulated therefrom) and entering the flanged head 38 of thecylinder 39.

The lower end of the cylinder 39 is threaded externally for thereception of a collar 54, having lugs 55. A ring 56 is disposed belowthe collar and insulated therefrom, said ring being held in place bymeans of insulated screws passing through the lugs of the collar 5a andthe flange of sleeve 51 and entering said ring 56. The arms of adepending bracket 57 are secured at their upper ends to the ring 56, andsaid bracket is provided at its lower end with a holder 58 for the lowercarbon 59. The ring 56 is provided near its periphery at diametricallyopposite points with holes for the passage of the upper ends of the armsof a depending yoke 60, the lower end of which carries a support 61 forthe bottom of the arc-inclosing globe 62. The upper ends of theyoke-arms are threaded and pass freely through the holes in the ring 56,and above said ring thumb-nuts 63 are screwed on the yoke-arms, by meansof which nuts the yoke can be adjusted to cause the upper end of thearc-inclosing globe to bear properly against its seaton the under faceof the ring 56. Aside from the ring 56 the cover for the inner globeconsists of a block 64 of porcelain or similar material having anannular flange 65 to rest upon a shoulder 66, formed in the ring 5.6,and also havingacentral hole for the passage of the uppercarhon. Theuppercarbon passes loosely through the block 64, leaving suflicientspace to permit the escape of gas from the inner globe to the cylinder38, from which a portion of said gas may escape through a hole 67 in thecylinder-head,th rough which the cl utchrod passes. Air will also enterthe cylinder 39 through the hole 87 and will mix with a portion of theair entering the latter from the inner globe. Now asthe temperaturewithin the innerglobe rises the gas in said globe will increase inpressure and escape to the cylinder 39. where it will become dilutedwith air or become charged more or less with oxygen by the decompositionof the air, and when the temperature in the globe decreases (tending toproducea partial vacuum) this diluted gas will be drawn-from thecylinder into the globe, these changes of temperature and consequentvarying pressures within the globe being brought about'by the varyingintensity of the are common in the practical operation of electric-arclamps.

With a lamp structure-such as hereinbelt'ore described in detail variousand, in fact, any form of regulating mechanism may be employed,according to the character of circuit and current with which it may bedesired to use the lamp; but in this case I have shown and will describeregulating mechanism which can be employed on a constant-potentialcircuit with eithera direct or an alternating current. A detaildescription of the regulating devices will now follow.

A clamp 68, constructed to be removably secured .to the carbon-guidetube or backbone 26, is provided with a laterally-projectingarrn 69,towhich a horizontally-disposed U- shaped spring 70 is secured at thejuncture of its two arms. Each arm of the spring 70 is provided at itsfree end with a depending lug 71, from which the spools 72 of theregulatorsolenoid are pivotally suspended. To effect the free pivotalconnection between the solenoid-spools 72 and the arms of the spring 70,bifurcated arms 7 3 are secured to the spools and terminate over thesame, preferably in line with their axes. The members of the arms areprovided with holes 74, and said members receive between them the lugs71, which depend from the arms of the spring 70, to which they arepivotally connected by means of pins 75 passing through the holes of thearms 74 and holes in the lugs 71. The cores 76 of the solenoid are madelaminated and connected at their lower ends by a cross-bar 77'that is tosay, each lamina is made U- shaped, so that when all the laminae aresecured togethera U-shaped core-frame will be produced the parallel armsof which will constitute the cores 76 and the portion connecting saidparallel arms will constitute the cross-bar 7 7 The cross-bar ofthecore'frame is mounted upon the upper member of an elliptical spring78, and the lower member of said spring is secured to a lug 79,projecting laterally from a sleeve 80. A clutch-rod 81 passes throughthe sleeve 80 and also through the sleeve 51 and head of cylinder 39 andis attached at its lower end to the carbon-clutch 82, disposed over theporcelain block or cover 64:. This clutch is of the ring type andcomprises a split ring 83, having ears 84 for the passage of aclamping-screw, and a ring 85, of steel, clamped in a groove 86 in saidsplit ring and insulated from the latter by means of suitable insulatingmaterial 87.- That portion of the clutch-rod 81 which passes through thesleeve 80 is provided with a series of notches 88, and a pin 89 passesthrough a hole in the sleeve 80 and through one of said notches. Bythese means the sleeve 80, and consequently the solenoid-cores, can beadjusted vertically relatively to the spools according to the voltage ofthe line on which the lamp is to be used. By pivotally suspending thespools of the solenoids and mounting the cores on a spring in the mannerabove explained proper operative alinement of the bores of the spoolsand the cores is insured during the operation of the lamp and the jarand vibration incident thereto and binding of the coresin the spools iseifectually prevented,because the spools will always accommodatethemselves to the cores, and vice versa. In order to avoid anypossibility of the cores coming in actual contact with the wall of thebore of the spools, light and preferably soft cushioning material isplaced on each core.

For the purpose of controlling the movement of the cores within thespools of the solenoids and to insure a slow and steady movement whenthe solenoids are acting to separate the carbons it has been common touse air-pots; but those heretofore in use have been found to be more orless defective in the accurate performance of the functions required ofthem. This defect is due largely to the employment of a plunger made ina single piece, which has to be made of sufiiciently less diameter thanthe internal diameter of the cylinder to permit the passage of a limitedportion of air. In view of the fact that for the reason stated theplunger was necessarily of appreciably less diameter than that of thebore of the cylinder it has been found to be impossible to maintain saidplunger concentric to the axis of the cylinder due to the jar andvibration of the mechanism of the lamp, and consequently at certaintimes a portion of the periphery of the single plunger will be in actualcontact with the wall of the cylinder, while at a diametrically oppositepoint on the plunger it will be twice as far as it should be from thewall of the cylinder. Thus a duct is formed of such large size as topermit the too free How of air, and consequently the too free movementof the plunger and in turn the too sudden movement of the regulatingdevices and the carbon. For the reasons above pointed out the movementsof the regulating mechanism due to the imperfections of the air-potconstruction heretofore in use have been spasmodic and irregular.Furthermore, with a plunger made of a single piece the relativediameters of the plunger and cylinder must be such as to leave a verysmall space for the passage of air between said plunger and the wall ofthe cylinder; otherwise the proper cushioning effect would not beobtained. It has been found in practice that the interior surface of thecylinder and the external surface of the plunger will become more orless so corroded as to interfere with the thin annular air-duct betweenthe plunger and' the wall of the cylinder and also to interfere with theproper movements of the plunger or cylinder relatively to each other. Aconstruction is therefore desirable in which such interference bycorrosion can be com pensated for, and this I accomplish in a mannerwhich will be presently explained. An arm 90 is secured to the upper endof the clutch-rod 81 and projects laterally therefrom. Below the freeend of this arm the cylinder 91 of the airpot is located, and the head92 of this cylinder is provided on its inner face-with a seat 93 for avalve 94. The shank 95 of the valve passes freely through a hole in thehead 92 and is pivotally attached at its upper end to the arm 90. Inthis manner the cylinder of the airpot is suspended. The plunger of theair-pot comprises a series of disks or laminae 96, constituting theplunger, and a plunger-rod 97, the latter being permanently secured atits lower end to the lamp-floor by means of a screw 98. The disks orlaminae are made with alined holes for the accommodation of theplunger-rod 98, and each of these holes is of slightly but appreciablygreater diameter than that of the rod 97, so that they will be capa-Isle of slight lateral movement, and the said disks or laminae each havea diameter slightly but appreciably less than that of the internaldiameter of the cylinder 91. The several disks are maintained in contactwith each other by means of a spring 99, encircling the rod 97 andbearing at its respective ends against the lower disk and thelamp-floor.

The upper disk of the series is secured to the plunger-rod preferably byriveting or upsettingthe upper end of the rod. Now experience shows thatthe disks will seldom, if ever, all be concentric with the plunger-rodand the bore of the cylinder at the same time; but. as a matter of fact,they will become variously disposed and the several disks will contactwith the wall of the cylinder at various points, the locus of thecontacting points being approximately equal to a circle marking theinner surface of the cylinder. The effect of this will be to cause thesectional plunger to contact with the wall of the cylinder approximatelythroughout the entire circumference, but the disposition of the disksform a tortuous duct for the passage of air, said duct having a capacityalways equal to that of an annular duct which would be formed betweenthe peripheral walls of the disks and the wall of the cylinderii' all ofsaid disks (or a plunger consisting of a single disk) could bemaintained disposed concentric to the plunger-rod and the axis of thecylinder. ThusI am enabled by the use of a plunger comprising a seriesof independent disks or laminae constructed and arranged as beforedescribed to insure the constant maintenance of a uniform action of theair-pot under all conditions, as well as a uniform and steady movementfrom one end of its throw to the other. Furthermore, I am enabled tomakeeach disk or lamina of appreciably less diameter relatively to theinternal diameter of the cylinder than would be possible with a plungermade of a single piece, because the locus of the contacting points ofthe several disks with the wallof the cylinder will approximatelyliewithin a circle marked by the internal wall of the cylinder regardlessof the diameter of each disk, and thus I am enabled to compensate forany interference by corrosion which would be encountered with a plungermade of a single piece, as before explained. It is apparent thatif thecapacity of the tortuous duct above referred to as being formed by theirregular disposition of the disks within the cylinder be increased theresistance to the movement of the cylinder relatively to the plungerwill be diminished, and thus the air-pot may be adjusted to offergreater or less mechanical resistance by adjusting the capacity of thesaid tortuous d not. This may be accomplished by separating certain ofthe disks by means of a washer 100 (see Fig. 6) of less diameter thanthat of the disks, the relative size of said washer to the diameter ofthe disks and the disposition of said washer between difierent pairs ofdisks controlling the size and capacity of the said tortuous passagefrom one end to the other of the series of disks. With the constructionshown in the drawings the action of the solenoids will be-to raise theairpot cylinder (thus closing the valve at the upper end thereof) andcause the air-pot to act as above explained to resist the pull of thesolenoids and insure the gradual rise of the upper carbon. When thecores of the solenoids descend, the air-cushion in the cylinder willcause the valve to open, the air to escape, and the cylinder to descendquickly. It is apparent that instead of making the cylinder of theair-pot movable it may be made stationary and the plunger connected withthe regulating mechanism. In such case the disposition of the air-potstructure would be the reverse to that shown in the drawings and thespring 99 dispensed with, as the disks would maintain contact with eachother by gravity.

Referring now to the lamp-circuits, it may be explained that currententering the lamp will flow from the positive binding-post by aconductor 101 to the solenoids and thence from the latter by conductor102 to the upper carbon, thence to the lower carbon, thence through aconductor 103 and a switch 104 to a resistance 105, and finally to thenegative binding-post of the lamp. If the lamp is to be used oneconstant-potential two-hundredand-twenty-volt circuit, thesolenoid-coils will be included in series with each other, as shown inFig. 16; but if it is to be used on a onehundred-and terrvolt circuitthe solenoid coils will be included 'in parallel with each other, asshown in Fig. 15., the reason for this difference growing out of thefact that it is common in practice to employ five'amperes on aone-huudred-and-ten-volt circuit and two and one-half amperes on atwo-hundred-andtwenty-volt circuit.

I have before explained that my lamp structure is adapted for use withthe regulating mechanism herein described) on constant-potentialcircuits employing either direct or alternatiug' currents, and in orderto transfer the lamp from a direct-current to an alternat ing-currentlamp it is necessary to displace the resistancecoil 105 by an inductiveresistance. The resistance-coil and'its support must therefore bereadily removable, and I will now proceed to describe the constructionand arrangement of the same and to point out certain advantageousfeatures thereof.

The frame or support 106 for the resistancecoil consists of a series ofexternally-grooved segments of porcelain which when assembled make acomplete ring having a series of circumferential grooves 10'? for thereception of the resistance-coil. Each segment is made with slots in thebases of the grooves for ventilating purposes, and the structure of eachsegment is strengthened by integral eross bars 108. The ridges betweenthe grooves are notched, as at 109, to permit the resistance-coil topass from one groove to another, and suitable provision is also made(such as perforated seats 110) for the attachment of binding-posts. Theresistance-coil is so constructed as to minimize the extent of itscontact with the support, so as to insure the greatest possible facilityfor ventilation. The resistance-coil is therefore formed irregulary, soas to present the appearance of a spiral groove 111, extending from endto end thereof, said groove forming a continuous air-duct and permittingthe coil to bear only at intervals against the segmental support. Thesegmental porcelain support for the resistancecoil is located in theenlarged upper portion 2 of the shell or casing, and each segment isdisposed upon a plate 113, and said plates are secured in turn to thehood 21 by means of bolts 114. By removing these bolts the segmentalsupport will be released, and then by removing the resistance-coil thesegments can be separated and removed from the lamp without disturbingthe backbone 26 or any other part of the lamp structure.

From the above description it will be seen that the resistance device issplit to permit it to be placed around or removed from around thecentral tube without the necessity of removing the hood.

IVhen the lamp is to be converted from a direct-current to analternating-current lamp, it is simply necessary to remove theresistance-coil, as above explained, and insert in its place aresistance-coil 115 of any desired construction, as shown in the diagramFig. 17.

Various slight changes might be made in the details of construction ofmy invention without departing from the spirit thereof or limiting itsscope, and hence I do not wish to limit myself to the precise detailsherein set forth.

Havingfully described my invention, whatI claim as new, and desire tosecure by Letters Patent, is

1. An arc-lamp structure comprising a central tube, a hood permanentlysecured thereto, split resistance and reactance devices, and means forinterchangeably supporting the same in place in the lamp.

2. In an electric-arc lamp, the combination with a hood and internalframework supported thereby, of a sheet'metal shell havinga closedperipheral wall and means for removably connecting said shell to thehood, whereby said shell can be lowered bodily to expose the internalframework.

In an electric-arc lamp, the combination with a hood and internalframework supported thereby, of a sheet-metal shell removably attachedto said hood, and an outer-globe holder supported by said shell.

4. In an electric-arc lamp, the combination with a hood, internalframework, regulator mechanism and an arc-inclosing globe supported bysaid hood, of a sheet-metal casing or shell removably attached to saidhood, an outer-globe cover at the lower end of said casing or shell, anda holder for said outer globe supported by said casing or shell.

5. In an electric-arc lamp, the combination with a hood, of a platesecured therein, binding-posts upon said hood, screws securing thebinding-posts to said plate, a backbone secured to said plate, and lampmechanism connected with said backbone.

6. In an electric-arc lamp, the combination with a hood having two holesin its top and having flanges surrounding said holes, of a plate withinthe hood having portions entering said holes, insulating materialbetween said plate and hood, sleeves mounted on the flanges on the hood,caps on said sleeves, and screws passing through said plate and sleevesand entering said caps.

7. The combination in an electric-arc lamp, of a central tube havingalateral hole near its lower end, a carbon-holder and an adjustable pinadapted to enter the hole near the lower end of the tube andbecome'disposed over the carbon-holder to facilitate the insertion of ashort rod of carbon thereinto.

8. The combination in an electric-arc lamp, of a central tube havingalateral opening near its lower end, a carbon-holder in said tube, atubular screw,means for supporting said screw in a horizontal position,a pin movable longitudinally through said tubular screw adapted to enterthe hole in the central tube and be come disposed over the carbon-holdertherein, and means for retaining said pin in its withdrawn position.

9. The combination in an electric-arc lamp, of a central tube having ahole near its lower end, a carbon-holder in said tube, a tubular screw,means for supporting said screw in a horizontal position in line withthe hole in the central tube, a longitudinally-movable pin in saidtubular screw, and a stop to be engaged by the outer end of said pin.

10. The combination in an electric-arc lam p, of a central tube having alateral hole near its lower end, a tubular screw, means for supportingsaid tubular screw in a horizontal position in line with the hole nearthe lower end of the central tube, said tubular screw having a slot inits wall, a pin movable longitudinally in said tubular screw, and an armon said pin to normally engage the end of the screw and pass through theslot therein when said pin is moved to enter the lateral hole in thecentral tube.

11. In an arc-lamp, the combination with a central tube or backbone, ofan annular sectional support embracing said central tube or backbone andsupported by the latter, and a resistance-coil wound upon said annularsectional support.

12. The combination in an are-lamp, of a coiled resistance-wire, and asectional support therefor on which said resistance wire is wound, thesections of said support being detachably connected together and to thelamp structure.

13. In an arc-lamp, the combination with the frame, and a series ofplates, of a resistancemace? 7 supporting device comprising severalremovable segments mounted, respectively, on said plates, boits securingsaid plates to the frame and a resistance-wire wound on said segments.

14. In an arclamp, the combination with the central tube or backbone anda plate secured to the upper end thereof, of a series of plates disposedbelow said first-mentioned plate, a segmental ring of insulatingmaterial having its segments mounted on the series of plates, andremovable bolts securing the said series of plates to the plate securedto the central tube or backbone of the lamp.

15. In an arc-lamp, the combination with a regulator-magnet and aclutch, of a connecting device between the regulator-magnet and theclutch, a retarding device comprising a cylinder and a plungerconsisting of a series of independent sections, one of said parts of theretarding device attached to a fixed support and the other part attachedto the said connecting device,

16. In an arc-lamp, the combination witha clutch-rod and aregulator-magnet connected therewith, of an arm projecting laterallyfrom said clutcha-od, an air-pot cylinder, a valve in the upper endthereof connected with and suspended from said arm, a plunger in saidcylinder, and a fixed support for the plungerrod of said plunger.

17. in an arc-lam p, the combination with a clutch-rod and aregulator-magnet connected with said rod, of an arm projecting laterallyfrom said rod, an air-pot cylinder, a valve in the upper end of saidcylinder attached to and suspended from said arm, a plunger-rod, and aplunger on said rod comprising several independent laterally-movabledisks, a fixed support for said plunger-rod and a spring between thelower disk of the series and said fixed support.

18. A clutch for an arc-lamp, comprising an annular frame having aninternal annular groove, ears projecting from the meeting ends of saidframe, a ring disposed within the grooved frame, insulating materialbetween said ring and frame and a. fastening device passing through theears of the frame.

19. In an electric-are lamp, the combination with regulator-magnets andtheir cores or armatures, of a. clutch, a clutch-rod, a eonnec tionbetween the cores or armature", of the regulator-magnets and theclutch-rod, an airpot cylinder suspended from said clutch-rod, a plungercomprising independently-movable disks in said air-pot cylinder, aplunger-rod on which said disks are loosely mounted and a fixed supportfor said plunger-rod.

20. In an electric-arc lamp, the combination with a central tube orbackbone, of a clamp secured thereto, a spring-plate secured to saidclamp and regulator-magnets secured to the free ends of saidspring-plate.

21. In an electric-arc lamp, the combination witha central tube orbackbone, of a U-shaped spring-plate embracing said central tube orbackbone, and regulator-magnets suspended from the free ends of saidspring-plate.

22. In an electric-arc lamp, the combination with a central tube orbackbone and arms projecting laterally therefrom, of helices pivotallyattached to and suspended from said arms, a yielding supportedcore-frame and sleeves of soft material on the arms of said coreframe.

In testimony whereof I have signed this specification in the presence oftwo subscribing witnesses.

' BERNARD A. STOWE. Witnesses:

ROBERT F. LAG'ANKE, FRANK A. Roonns.

